Visual electron flow indicator



June 10, 1952 L. s. MALOOF VISUAL ELECTRON FLOW INDICATOR Filed Feb. 20 1951 fave-radar Zfeaw 15'. Malay)" I y mjww IV/ ammy??? Emil Fwmmmmmm N.

Patented June 10, 1952 UNITED ES PT ENT F 2500003 VISUA E I ELSEG'ERON FLOW Which-T018- Eeom S2: Malcof, Watertown; Mass.- appiieatiafl etraary 20, 1951, SerIal'Nd; mm-

6 (filaimsv with: thetremendous develiipmeh't and increasing complexity ofmodem radar: electronic and communicatiohs equipment" the: problemof quick,- efiicien't ser' viee: and maintenane' becomes an important factor; 8

The needof some? simple,- quikamt iriiaiiible technique or device to facilitate the service and maintenaneecf ali types of electronic equipment i's vita'l;

Accordingly it the principal object of inventionto: provide a means win ejifelcsy it is; nos sible' Visually to determinewhethefi a vacuum tubeis'iunetionirig: properly while under normal operating-conditions:- v

other 0bject are to provide; means fci testing vacuum tubes which: do not: require: theof externalequipment. suolias' thbemhebkers; meters or: oscilloscopesz. whichv doesnot alter the ewe tr ical characteristics ofth associated circuit of the tube being" tested,. which: can b'e' u's'eii in the circuits of existing apparatus withotitaltera tion, modificationor" additions thereto"; which does: not require that v the time being: tested be removedfi'dm its socket: or the asso'ciated equip-- ment be: shut down; which-gives a continues indication; which does not: require any al skill or techniques to use}? which may b'e readily incorporated in existingityifiesoi le'cti'b'n thbes'z which does: not increase" theinter ='eleot'bde -ca paeities'or alter-theriormal chaiafcteiist s'fdf th'e tube with which it" is "used;v Whiclids sa a use: which is' economical to manuraet e which can be produced by mass productiofi teehfiiqiis.

In a broad aspect the invention contemplates coating or otherwise applvingtoa selected area of one of the-positively char'ged electrodes of a vacuum tube, vfor example the anode' or the screen grid;.a-ph'osphorsuch-as Will'imite, zinc phosphate, zinc sulphide with nickel or any other material which glows or fluoresces under the 'in fiuenee of a beam of electrons". The phosphor ooated areaof the electrode is chosen so that it is i-n-the: path of the operational flow of 'elec trons fromthe; emitting electrode or cathode- 1:0 the-positively charged electrode and at the same time is visible through the transparent envelope enclosing the tube electrode or in tubes having an opaque envelope visible through-a window therein so that the fluorescence of thephos'phor can-be observed. The presence of the fiuorescing of the spot indicatesthe presence of the normal operational electron flow, the brilliancy ofthe fluorescence being a fu'nction of the quantity of the' electron flow, andwith experience a tech= niciari can readily determine thenormai fluores= ci'n'g which iifdicaite'sfthat tli-tu be and: associated cir ouit are fiei foi miiig normallyz I I) ma; meresp eifie'as'peot an: elongated s ot or stiip of a suitable fiho's'phor is applied to an elongated plane surface of: a" tube; anode which is substantia11m5aaa11e1:to: the electi'on emitting tubecathode so: that sgicstiis in -the" path: of such-emitteu ei'e'eti'ons which co'h itiite the nofi maleperatitna --elec;t on fiwim a double triode tube-such aetls-ie tyne 6J6:having channel shaped anodes, elongated spots are applied t6 -dri'e' or bot'h o'fl thefi'ange portions o'f each-otthe arfdtles of the tube' afdjacnfi theifi'jufictibii withtlir spe'etive web: portions wh re v the r spots are both visible and a in: the f-uhctiofial new at el'btr 'dil's fromthetabe'eathod.

These and other objects: and; aspects will be apparent from tiie foliowin zdescription of a sfie' cific embodiment: of the invention refer'ringa to a drawing wherein:

Eig zl is aside elevation o't an eiectronic discharge deviceeinbodyifig the inve'zitio'm Fig.2 is anenIaJ-rged sectional view online 2 2 of Fig 1-; and A Fig. 3 is: an-- isometric view of the electrodes of'the device= own inFig; 1': with-the envelope and: other portions brcien away; 7 a

The electronic: discharge device" illustrateh in Fig; 1- is a double: triode vacuum tube having: a commoncathode lit and is of generally similar construction to' the 1 ofvacuum tube desig nated fiflfi; The cathode l 0 1s; 'Of 'th conventional cbatdltype ehc-losing. aim electrical heater- (riot shown) which is energized from an external power source thr'oughtwd- I 1': extending downwardly fiom the tube base I Z: Whenthe heater raise's the tempiaitureof the cathode Hi to a dull red} its coated stir-face M cfiiously eiriits el'ctronsi.inthe well kndwri niainri'e'i' which comprises ne'- part of this inventioir and need net be'fleser-ibed in ffirther 'det3il.- Theopposite ends of' tlie c'atlao'ch-z' Ilt are-supported respectively by two r spacers" {-6 which ar'e generally circi'ilar in form an'd provided with peripherally extending tztbs I forbearifig against the iifside ofalt-em c l'osing4glasenvelofi202 The sfiaceis IB also-'sufiizort two amodes 21, one: of whicliis i)o'si'ticmect-on eith'eisiiie oi th cathode loizi-mranetreiatithsiii theretw of thea nQde's Z't 'i's getter-aim chafinl- 's'hffid cross'setiom'cbnsistingaditaj tteb pe t Emithim is'positiond -afdiacefit"tli cathtae *0 ai iu twt fla ge: b'rtions 2e integ-ia i matted wit a bentback norma ly tt' wfittitio se t at the flange portions eitefid oiitwitdli'atwayffoifi 3 the cathode. Attached to the upper end of one of the anodes 22 is a rod 30 (Fig. l) at whose upper end is a horizontal member 32 carrying a pan 34 for the getter used to exhaust the tube.

Connections from the cathode l0 and anodes 22 to external circuits are made through pins extending from the base, pin 2| being connected internally to the cathode and pins 23 with the respective anodes. When the negative and positive terminals of a conventional source applying a direct potential, such as a battery or rectifier, are connected respectively to the pin 2i and either of the pins 23, the potential difference is applied between the heated cathode surface I l and the anode 22 which causes the electrons emitted by the cathode to flow to the anode. The flow of such electrons is controlled by an electrode 40 consisting of a plurality of parallel conductors such as the small wires 42 which extend between two mounting supports such as the post 44 located upon either side of an associated anode 22 so that the wires are in the path of the flow of electrons. A similar control electrode is interposed between the cathode IO and the other anode 22. The respective control electrodes 40 are connected internally with pins 25 so that the potentialof either control electrode with respect to the cathode l0 can be varied thereby to control the number of electrons flowing to the correlated anode 22.

The presence of the above described electron flow is visually indicated by the fluorescing of two elongated spots of a phosphor such asWil1imite one of which is applied to a surface of each of the respective anodes which is in the path of the electrons. Although in some types of tubes wherein the spacing between the cathodes and the anode is greater, it is possible to apply the spot of phosphor to the anode surface directly options 26 have been found to receive suflicient flow of electrons from the emitting surface [4 of the cathode to cause the phosphor to fluoresce, the effect is greater nearer the cathode so that it is preferable to locate the phosphor spot on the flanged portion 26 of the anode as at 50 (Fig. 3) adjacent the junction with the web portion 24 of the anode 22. Although I have shown a phosphor spot 50 on only one flange portion 26 of each anode 22, it is to be understood that it is within the scope of this invention'to apply spots to both flange portions of each anode so that the electron flow can be checked from either side of the tube.

,As the presence of the'phosphor spots 50 has beenfound in no way to effect the performance or characteristics of the tube, it can be used as a replacement for its conventional prototype without any change in the associate circuit. When the tube is operating normally the phosphor spots 50 fluoresce brilliantly enough so that they can be seen at a distance of several feet in illumination of ordinary intensity so that by observing that the fluorescence is of normal brilliancy a technician can visually determine without the need of any test instrument or tube checker that the following conditions prevail:

(1) The emission of the cathode is sufficient.

(2) The power supply impressing voltage upon the anode is operating satisfactory.

(3) The tube is conducting i. e. the presence of plate current.

(4) Present and relative strength of modulated input carrier signals.

It is thus possible in apparatus such as computors where large numbers of similar tubes are used, quickly to find faulty tubes by observation of the relative brilliancy of the respective phosphor spots in adjacent tubes thus greatly reducing the time required to isolate the tube or circuit wherein the fault is located. The possibility of visual checking the tubes also reduces the chance of obtaining incorrect results due to an undetected failure of some portion of the computor and thus permits the elimination of expensive and complicated auxiliary checking circuits, thereby minimizing the cost of construction.

Tubes incorporating the above described phosphor spots also have application in less complex circuits such as in communication and radar equipment used by the armed forces, airlines and railroads, the continuous functioning of which is a vital matter. In such equipment the technician can determine by the reduction in the brilliancy of the fluorescence of the phosphor spots the tubes in which the emission is reduced without removing the tubes from their sockets thus reducing the maintenance time required for routine checks and eliminating to a great extent the necessity for periodic replacement of all tubes.

Although I have found that for general applications the brilliant green fluorescence of Willimite is the most satisfactory color, for special purposes other phosphors having different fluoresoing colors can be used to advantage. For example by the use of different phosphors upon the respective anodes 22, it is possible to determine when the tube is used in a flip-flop circuit which half of the tube is conducting. It is also possible to use different phosphors in tubes of the same or other types which are used for different purposes making it possible, for example, for a technician to determine visually the tubes in the high, intermediate. and audio frequency stages 01 having-special functions.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. An electron discharge device of the type having a transparent enclosing envelope, a cathode having a heated surface for emitting electrons, an anode having a surface substantially parallel to the cathode and spaced at a distance therefrom, means connecting the cathode and the anode to the negative and positive terminals respectively of a direct potential source thereby to cause a flow of electrons between the surfaces, a control electrode having a plurality of conductors interposed between the surfaces transversely to the direction of the flow of electrons, and a spot of a phosphor on the anode, said spot being visible externally the envelope, said spot being located in the path of the fringe flow of the electrons through the control electrode and shielded from the heat of said cathode;

2. An electron discharge device of the type having a transparent enclosing envelope, a cathode having a heated surface for emitting electrons, an anode having an elongated plane surface substantially parallel to the cathode and spaced at a distance therefrom, means connecting the cathode and the anode to the negative and positive terminals respectively of a direct potential source thereby to cause a flow of electrons between the surfaces, a control electrode having a plurality of conductors interposed between the surfaces transversely to the direction of the flow of electrons, and a spot of a phosphor on the elongated plane surface of the anode, said spot being visible externally the envelope, said spot being located in the path of the fringe flow of the elece trons through the control electrode and shielded from the heat of the cathode.

3. An electron discharge device of the type having a transparent enclosing envelope, a cathode having a heated surface for emitting electrons, an anode having at least two elongated plane surfaces substantially parallel to the cathode and spaced at a distance therefrom, the first of said surfaces facing said cathode, the second surface being substantially normally disposed to the first surface, means connecting the cathode and the anode to the negative and positive terminals respectively of a direct potential source thereby to cause a flow of electrons between the surfaces, a control electrode having a plurality of conductors interposed between the surfaces transversely to the direction of the flow of electrons, and a spot of a phosphor applied to the second plane surface of the anode, said spot being visible externally the envelope, said spot being located in the path of the fringe flow of the electrons through the control electrode and shielded from the heat of said cathode.

4. An electron discharge device of the type having a transparent enclosing envelope, a heated cathode having a surface for emitting electrons, an anode spaced at a distance from cathode, said anode being in the form of a channel with its web portion parallel to a portion of the emitting surface of the cathode and its flanged portions extending away therefrom, means connecting the cathode and anode to the negative and positive terminals respectively of a direct potential source thereby to cause a flow of electrons between the cathode and the anode surface, an elongated spot of a phosphor applied to one of the flanged pottions adjacent its junction with the web portion of the anode, said spot being visible externally of the tube, said spot being located in the path of the fringe flow of electrons from said cathode to said anode and shielded from the heat of said cathode.

5. A vacuum tube comprising an electron emitting cathode, an anode having a surface parallel to the cathode, and a spot of phosphor material on the anode, said spot being visible externally of the tube, said spot being located in the path of the fringe flow of electrons from said cathode to said anode and shielded from the heat of said cathode.

6. A vacuum tube comprising an electron emitting cathode and a channel shaped anode having its web portion parallel to said cathode and its flanged portions extending away therefrom, and a spot of phosphor material applied to the outer surface of one of the flanged portions of the anode adjacent the junction with the web'portion, said spot being visible externally of the tube, said spot being located in the path of the fringe flow of electrons from said cathode to said anode and shielded from the heat of said cathode.

LEON S. NIALOOF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,994,726 Orth Mar. v19, 1935 2,113,669 Thompson Apr. 12, 1938 2,130,162 Thompson Sept. 13, 1938 2,175,690 Happe, Jr Oct. 10,1939 2,175,700 Roberts Oct. 10, 1939 2,197,341 Jonker Apr. 16, 1940 2,223,285 Heins Nov. 26, 1940 2,243,034 Heins May 20, 1941 2,273,800 Jensen Feb. 17, 1942 2,394,857 Hultquist Feb. 12, 1946 2,564,737 Szegho Aug. 21, 1951 2,565,533 Szegho Aug. 28, 1951 

